Trading on Margin

First a little background: I'm on Binance Global and I usually trade only on spot so I can only go long trades. I am now more confident with my TA, that I would like to go shorts since we are in a bear market. You can't go short trades on spot unless you have the coin to short with right? Anyway for simplicity:

play money: U$ 100

risk/reward is 2:1 so lets say TP at 2% and SL at 1%

lets forgo the trading fees for now

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Q1 : for example I go isolated 10x on BTC/USDT so it means my U$ 100 becomes U$ 1000 and I short it and goes 2% down and I TP. 2% of 1000 is 20 so now my funds are U$ 120?

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Q2 : if it goes the other way and it triggers my SL it means I loose $10 (1% of 1000 is 10). If this is the case if I didn't put a SL and it goes 10%, I loose everything or Liquidated?

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Q3 : I've heard that if you trade vs BUSD instead of USDT you get little or no trading fees?